ddr: imx: Add i.MX9 DDR controller driver

Since i.MX9 uses same DDR PHY with i.MX8M, split the DDRPHY to a common
directory under imx, then use dedicated ddr controller driver for each
iMX9 and iMX8M.

The DDRPHY registers are space compressed, so it needs conversion to
access the DDRPHY address. Introduce a common PHY address remap function
for both iMX8M and iMX9 for all PHY registers accessing.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>